Reread this quotation from near the end of “walden pond”: many a forenoon have i stolen away, preferring to spend thus the most valued part of the day; for i was rich, if not in money, in sunny hours and summer days, and spent them lavishly; nor do i regret that i did not waste more of them in the workshop or the teacher’s desk. explain this quotation. be sure to address the “wealth” thoreau claims, his use of that wealth, and his views of the workshop or school

I assume he's saying he's glad he spent his days the way he did, he enjoyed life for what it was worth outside of business, and even though he was not rich, he was still happy. He doesn't regret the fact that he wasn't working, to him. He's saying it would of been wasted time indoors, unable to experience life for what it's worth past the currency of the world. In the beginning I'm sure he was also stating that you should never waste people's time, and have them work for you.